[PATCH] device-mapper: Trigger an event when a table is deleted
[linux-2.6] / drivers / md / dm-mpath.c
1 /*
2  * Copyright (C) 2003 Sistina Software Limited.
3  * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4  *
5  * This file is released under the GPL.
6  */
7
8 #include "dm.h"
9 #include "dm-path-selector.h"
10 #include "dm-hw-handler.h"
11 #include "dm-bio-list.h"
12 #include "dm-bio-record.h"
13
14 #include <linux/ctype.h>
15 #include <linux/init.h>
16 #include <linux/mempool.h>
17 #include <linux/module.h>
18 #include <linux/pagemap.h>
19 #include <linux/slab.h>
20 #include <linux/time.h>
21 #include <linux/workqueue.h>
22 #include <asm/atomic.h>
23
24 #define MESG_STR(x) x, sizeof(x)
25
26 /* Path properties */
27 struct pgpath {
28         struct list_head list;
29
30         struct priority_group *pg;      /* Owning PG */
31         unsigned fail_count;            /* Cumulative failure count */
32
33         struct path path;
34 };
35
36 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
37
38 /*
39  * Paths are grouped into Priority Groups and numbered from 1 upwards.
40  * Each has a path selector which controls which path gets used.
41  */
42 struct priority_group {
43         struct list_head list;
44
45         struct multipath *m;            /* Owning multipath instance */
46         struct path_selector ps;
47
48         unsigned pg_num;                /* Reference number */
49         unsigned bypassed;              /* Temporarily bypass this PG? */
50
51         unsigned nr_pgpaths;            /* Number of paths in PG */
52         struct list_head pgpaths;
53 };
54
55 /* Multipath context */
56 struct multipath {
57         struct list_head list;
58         struct dm_target *ti;
59
60         spinlock_t lock;
61
62         struct hw_handler hw_handler;
63         unsigned nr_priority_groups;
64         struct list_head priority_groups;
65         unsigned pg_init_required;      /* pg_init needs calling? */
66         unsigned pg_init_in_progress;   /* Only one pg_init allowed at once */
67
68         unsigned nr_valid_paths;        /* Total number of usable paths */
69         struct pgpath *current_pgpath;
70         struct priority_group *current_pg;
71         struct priority_group *next_pg; /* Switch to this PG if set */
72         unsigned repeat_count;          /* I/Os left before calling PS again */
73
74         unsigned queue_io;              /* Must we queue all I/O? */
75         unsigned queue_if_no_path;      /* Queue I/O if last path fails? */
76         unsigned saved_queue_if_no_path;/* Saved state during suspension */
77
78         struct work_struct process_queued_ios;
79         struct bio_list queued_ios;
80         unsigned queue_size;
81
82         struct work_struct trigger_event;
83
84         /*
85          * We must use a mempool of mpath_io structs so that we
86          * can resubmit bios on error.
87          */
88         mempool_t *mpio_pool;
89 };
90
91 /*
92  * Context information attached to each bio we process.
93  */
94 struct mpath_io {
95         struct pgpath *pgpath;
96         struct dm_bio_details details;
97 };
98
99 typedef int (*action_fn) (struct pgpath *pgpath);
100
101 #define MIN_IOS 256     /* Mempool size */
102
103 static kmem_cache_t *_mpio_cache;
104
105 struct workqueue_struct *kmultipathd;
106 static void process_queued_ios(void *data);
107 static void trigger_event(void *data);
108
109
110 /*-----------------------------------------------
111  * Allocation routines
112  *-----------------------------------------------*/
113
114 static struct pgpath *alloc_pgpath(void)
115 {
116         struct pgpath *pgpath = kmalloc(sizeof(*pgpath), GFP_KERNEL);
117
118         if (pgpath) {
119                 memset(pgpath, 0, sizeof(*pgpath));
120                 pgpath->path.is_active = 1;
121         }
122
123         return pgpath;
124 }
125
126 static inline void free_pgpath(struct pgpath *pgpath)
127 {
128         kfree(pgpath);
129 }
130
131 static struct priority_group *alloc_priority_group(void)
132 {
133         struct priority_group *pg;
134
135         pg = kmalloc(sizeof(*pg), GFP_KERNEL);
136         if (!pg)
137                 return NULL;
138
139         memset(pg, 0, sizeof(*pg));
140         INIT_LIST_HEAD(&pg->pgpaths);
141
142         return pg;
143 }
144
145 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
146 {
147         struct pgpath *pgpath, *tmp;
148
149         list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
150                 list_del(&pgpath->list);
151                 dm_put_device(ti, pgpath->path.dev);
152                 free_pgpath(pgpath);
153         }
154 }
155
156 static void free_priority_group(struct priority_group *pg,
157                                 struct dm_target *ti)
158 {
159         struct path_selector *ps = &pg->ps;
160
161         if (ps->type) {
162                 ps->type->destroy(ps);
163                 dm_put_path_selector(ps->type);
164         }
165
166         free_pgpaths(&pg->pgpaths, ti);
167         kfree(pg);
168 }
169
170 static struct multipath *alloc_multipath(void)
171 {
172         struct multipath *m;
173
174         m = kmalloc(sizeof(*m), GFP_KERNEL);
175         if (m) {
176                 memset(m, 0, sizeof(*m));
177                 INIT_LIST_HEAD(&m->priority_groups);
178                 spin_lock_init(&m->lock);
179                 m->queue_io = 1;
180                 INIT_WORK(&m->process_queued_ios, process_queued_ios, m);
181                 INIT_WORK(&m->trigger_event, trigger_event, m);
182                 m->mpio_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
183                                               mempool_free_slab, _mpio_cache);
184                 if (!m->mpio_pool) {
185                         kfree(m);
186                         return NULL;
187                 }
188         }
189
190         return m;
191 }
192
193 static void free_multipath(struct multipath *m)
194 {
195         struct priority_group *pg, *tmp;
196         struct hw_handler *hwh = &m->hw_handler;
197
198         list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
199                 list_del(&pg->list);
200                 free_priority_group(pg, m->ti);
201         }
202
203         if (hwh->type) {
204                 hwh->type->destroy(hwh);
205                 dm_put_hw_handler(hwh->type);
206         }
207
208         mempool_destroy(m->mpio_pool);
209         kfree(m);
210 }
211
212
213 /*-----------------------------------------------
214  * Path selection
215  *-----------------------------------------------*/
216
217 static void __switch_pg(struct multipath *m, struct pgpath *pgpath)
218 {
219         struct hw_handler *hwh = &m->hw_handler;
220
221         m->current_pg = pgpath->pg;
222
223         /* Must we initialise the PG first, and queue I/O till it's ready? */
224         if (hwh->type && hwh->type->pg_init) {
225                 m->pg_init_required = 1;
226                 m->queue_io = 1;
227         } else {
228                 m->pg_init_required = 0;
229                 m->queue_io = 0;
230         }
231 }
232
233 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg)
234 {
235         struct path *path;
236
237         path = pg->ps.type->select_path(&pg->ps, &m->repeat_count);
238         if (!path)
239                 return -ENXIO;
240
241         m->current_pgpath = path_to_pgpath(path);
242
243         if (m->current_pg != pg)
244                 __switch_pg(m, m->current_pgpath);
245
246         return 0;
247 }
248
249 static void __choose_pgpath(struct multipath *m)
250 {
251         struct priority_group *pg;
252         unsigned bypassed = 1;
253
254         if (!m->nr_valid_paths)
255                 goto failed;
256
257         /* Were we instructed to switch PG? */
258         if (m->next_pg) {
259                 pg = m->next_pg;
260                 m->next_pg = NULL;
261                 if (!__choose_path_in_pg(m, pg))
262                         return;
263         }
264
265         /* Don't change PG until it has no remaining paths */
266         if (m->current_pg && !__choose_path_in_pg(m, m->current_pg))
267                 return;
268
269         /*
270          * Loop through priority groups until we find a valid path.
271          * First time we skip PGs marked 'bypassed'.
272          * Second time we only try the ones we skipped.
273          */
274         do {
275                 list_for_each_entry(pg, &m->priority_groups, list) {
276                         if (pg->bypassed == bypassed)
277                                 continue;
278                         if (!__choose_path_in_pg(m, pg))
279                                 return;
280                 }
281         } while (bypassed--);
282
283 failed:
284         m->current_pgpath = NULL;
285         m->current_pg = NULL;
286 }
287
288 static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio,
289                   unsigned was_queued)
290 {
291         int r = 1;
292         unsigned long flags;
293         struct pgpath *pgpath;
294
295         spin_lock_irqsave(&m->lock, flags);
296
297         /* Do we need to select a new pgpath? */
298         if (!m->current_pgpath ||
299             (!m->queue_io && (m->repeat_count && --m->repeat_count == 0)))
300                 __choose_pgpath(m);
301
302         pgpath = m->current_pgpath;
303
304         if (was_queued)
305                 m->queue_size--;
306
307         if ((pgpath && m->queue_io) ||
308             (!pgpath && m->queue_if_no_path)) {
309                 /* Queue for the daemon to resubmit */
310                 bio_list_add(&m->queued_ios, bio);
311                 m->queue_size++;
312                 if ((m->pg_init_required && !m->pg_init_in_progress) ||
313                     !m->queue_io)
314                         queue_work(kmultipathd, &m->process_queued_ios);
315                 pgpath = NULL;
316                 r = 0;
317         } else if (!pgpath)
318                 r = -EIO;               /* Failed */
319         else
320                 bio->bi_bdev = pgpath->path.dev->bdev;
321
322         mpio->pgpath = pgpath;
323
324         spin_unlock_irqrestore(&m->lock, flags);
325
326         return r;
327 }
328
329 /*
330  * If we run out of usable paths, should we queue I/O or error it?
331  */
332 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path)
333 {
334         unsigned long flags;
335
336         spin_lock_irqsave(&m->lock, flags);
337
338         m->saved_queue_if_no_path = m->queue_if_no_path;
339         m->queue_if_no_path = queue_if_no_path;
340         if (!m->queue_if_no_path && m->queue_size)
341                 queue_work(kmultipathd, &m->process_queued_ios);
342
343         spin_unlock_irqrestore(&m->lock, flags);
344
345         return 0;
346 }
347
348 /*-----------------------------------------------------------------
349  * The multipath daemon is responsible for resubmitting queued ios.
350  *---------------------------------------------------------------*/
351
352 static void dispatch_queued_ios(struct multipath *m)
353 {
354         int r;
355         unsigned long flags;
356         struct bio *bio = NULL, *next;
357         struct mpath_io *mpio;
358         union map_info *info;
359
360         spin_lock_irqsave(&m->lock, flags);
361         bio = bio_list_get(&m->queued_ios);
362         spin_unlock_irqrestore(&m->lock, flags);
363
364         while (bio) {
365                 next = bio->bi_next;
366                 bio->bi_next = NULL;
367
368                 info = dm_get_mapinfo(bio);
369                 mpio = info->ptr;
370
371                 r = map_io(m, bio, mpio, 1);
372                 if (r < 0)
373                         bio_endio(bio, bio->bi_size, r);
374                 else if (r == 1)
375                         generic_make_request(bio);
376
377                 bio = next;
378         }
379 }
380
381 static void process_queued_ios(void *data)
382 {
383         struct multipath *m = (struct multipath *) data;
384         struct hw_handler *hwh = &m->hw_handler;
385         struct pgpath *pgpath = NULL;
386         unsigned init_required = 0, must_queue = 1;
387         unsigned long flags;
388
389         spin_lock_irqsave(&m->lock, flags);
390
391         if (!m->queue_size)
392                 goto out;
393
394         if (!m->current_pgpath)
395                 __choose_pgpath(m);
396
397         pgpath = m->current_pgpath;
398
399         if ((pgpath && !m->queue_io) ||
400             (!pgpath && !m->queue_if_no_path))
401                 must_queue = 0;
402
403         if (m->pg_init_required && !m->pg_init_in_progress) {
404                 m->pg_init_required = 0;
405                 m->pg_init_in_progress = 1;
406                 init_required = 1;
407         }
408
409 out:
410         spin_unlock_irqrestore(&m->lock, flags);
411
412         if (init_required)
413                 hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path);
414
415         if (!must_queue)
416                 dispatch_queued_ios(m);
417 }
418
419 /*
420  * An event is triggered whenever a path is taken out of use.
421  * Includes path failure and PG bypass.
422  */
423 static void trigger_event(void *data)
424 {
425         struct multipath *m = (struct multipath *) data;
426
427         dm_table_event(m->ti->table);
428 }
429
430 /*-----------------------------------------------------------------
431  * Constructor/argument parsing:
432  * <#multipath feature args> [<arg>]*
433  * <#hw_handler args> [hw_handler [<arg>]*]
434  * <#priority groups>
435  * <initial priority group>
436  *     [<selector> <#selector args> [<arg>]*
437  *      <#paths> <#per-path selector args>
438  *         [<path> [<arg>]* ]+ ]+
439  *---------------------------------------------------------------*/
440 struct param {
441         unsigned min;
442         unsigned max;
443         char *error;
444 };
445
446 #define ESTR(s) ("dm-multipath: " s)
447
448 static int read_param(struct param *param, char *str, unsigned *v, char **error)
449 {
450         if (!str ||
451             (sscanf(str, "%u", v) != 1) ||
452             (*v < param->min) ||
453             (*v > param->max)) {
454                 *error = param->error;
455                 return -EINVAL;
456         }
457
458         return 0;
459 }
460
461 struct arg_set {
462         unsigned argc;
463         char **argv;
464 };
465
466 static char *shift(struct arg_set *as)
467 {
468         char *r;
469
470         if (as->argc) {
471                 as->argc--;
472                 r = *as->argv;
473                 as->argv++;
474                 return r;
475         }
476
477         return NULL;
478 }
479
480 static void consume(struct arg_set *as, unsigned n)
481 {
482         BUG_ON (as->argc < n);
483         as->argc -= n;
484         as->argv += n;
485 }
486
487 static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
488                                struct dm_target *ti)
489 {
490         int r;
491         struct path_selector_type *pst;
492         unsigned ps_argc;
493
494         static struct param _params[] = {
495                 {0, 1024, ESTR("invalid number of path selector args")},
496         };
497
498         pst = dm_get_path_selector(shift(as));
499         if (!pst) {
500                 ti->error = ESTR("unknown path selector type");
501                 return -EINVAL;
502         }
503
504         r = read_param(_params, shift(as), &ps_argc, &ti->error);
505         if (r)
506                 return -EINVAL;
507
508         r = pst->create(&pg->ps, ps_argc, as->argv);
509         if (r) {
510                 dm_put_path_selector(pst);
511                 ti->error = ESTR("path selector constructor failed");
512                 return r;
513         }
514
515         pg->ps.type = pst;
516         consume(as, ps_argc);
517
518         return 0;
519 }
520
521 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
522                                struct dm_target *ti)
523 {
524         int r;
525         struct pgpath *p;
526
527         /* we need at least a path arg */
528         if (as->argc < 1) {
529                 ti->error = ESTR("no device given");
530                 return NULL;
531         }
532
533         p = alloc_pgpath();
534         if (!p)
535                 return NULL;
536
537         r = dm_get_device(ti, shift(as), ti->begin, ti->len,
538                           dm_table_get_mode(ti->table), &p->path.dev);
539         if (r) {
540                 ti->error = ESTR("error getting device");
541                 goto bad;
542         }
543
544         r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
545         if (r) {
546                 dm_put_device(ti, p->path.dev);
547                 goto bad;
548         }
549
550         return p;
551
552  bad:
553         free_pgpath(p);
554         return NULL;
555 }
556
557 static struct priority_group *parse_priority_group(struct arg_set *as,
558                                                    struct multipath *m,
559                                                    struct dm_target *ti)
560 {
561         static struct param _params[] = {
562                 {1, 1024, ESTR("invalid number of paths")},
563                 {0, 1024, ESTR("invalid number of selector args")}
564         };
565
566         int r;
567         unsigned i, nr_selector_args, nr_params;
568         struct priority_group *pg;
569
570         if (as->argc < 2) {
571                 as->argc = 0;
572                 ti->error = ESTR("not enough priority group aruments");
573                 return NULL;
574         }
575
576         pg = alloc_priority_group();
577         if (!pg) {
578                 ti->error = ESTR("couldn't allocate priority group");
579                 return NULL;
580         }
581         pg->m = m;
582
583         r = parse_path_selector(as, pg, ti);
584         if (r)
585                 goto bad;
586
587         /*
588          * read the paths
589          */
590         r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
591         if (r)
592                 goto bad;
593
594         r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
595         if (r)
596                 goto bad;
597
598         nr_params = 1 + nr_selector_args;
599         for (i = 0; i < pg->nr_pgpaths; i++) {
600                 struct pgpath *pgpath;
601                 struct arg_set path_args;
602
603                 if (as->argc < nr_params)
604                         goto bad;
605
606                 path_args.argc = nr_params;
607                 path_args.argv = as->argv;
608
609                 pgpath = parse_path(&path_args, &pg->ps, ti);
610                 if (!pgpath)
611                         goto bad;
612
613                 pgpath->pg = pg;
614                 list_add_tail(&pgpath->list, &pg->pgpaths);
615                 consume(as, nr_params);
616         }
617
618         return pg;
619
620  bad:
621         free_priority_group(pg, ti);
622         return NULL;
623 }
624
625 static int parse_hw_handler(struct arg_set *as, struct multipath *m,
626                             struct dm_target *ti)
627 {
628         int r;
629         struct hw_handler_type *hwht;
630         unsigned hw_argc;
631
632         static struct param _params[] = {
633                 {0, 1024, ESTR("invalid number of hardware handler args")},
634         };
635
636         r = read_param(_params, shift(as), &hw_argc, &ti->error);
637         if (r)
638                 return -EINVAL;
639
640         if (!hw_argc)
641                 return 0;
642
643         hwht = dm_get_hw_handler(shift(as));
644         if (!hwht) {
645                 ti->error = ESTR("unknown hardware handler type");
646                 return -EINVAL;
647         }
648
649         r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv);
650         if (r) {
651                 dm_put_hw_handler(hwht);
652                 ti->error = ESTR("hardware handler constructor failed");
653                 return r;
654         }
655
656         m->hw_handler.type = hwht;
657         consume(as, hw_argc - 1);
658
659         return 0;
660 }
661
662 static int parse_features(struct arg_set *as, struct multipath *m,
663                           struct dm_target *ti)
664 {
665         int r;
666         unsigned argc;
667
668         static struct param _params[] = {
669                 {0, 1, ESTR("invalid number of feature args")},
670         };
671
672         r = read_param(_params, shift(as), &argc, &ti->error);
673         if (r)
674                 return -EINVAL;
675
676         if (!argc)
677                 return 0;
678
679         if (!strnicmp(shift(as), MESG_STR("queue_if_no_path")))
680                 return queue_if_no_path(m, 1);
681         else {
682                 ti->error = "Unrecognised multipath feature request";
683                 return -EINVAL;
684         }
685 }
686
687 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
688                          char **argv)
689 {
690         /* target parameters */
691         static struct param _params[] = {
692                 {1, 1024, ESTR("invalid number of priority groups")},
693                 {1, 1024, ESTR("invalid initial priority group number")},
694         };
695
696         int r;
697         struct multipath *m;
698         struct arg_set as;
699         unsigned pg_count = 0;
700         unsigned next_pg_num;
701
702         as.argc = argc;
703         as.argv = argv;
704
705         m = alloc_multipath();
706         if (!m) {
707                 ti->error = ESTR("can't allocate multipath");
708                 return -EINVAL;
709         }
710
711         r = parse_features(&as, m, ti);
712         if (r)
713                 goto bad;
714
715         r = parse_hw_handler(&as, m, ti);
716         if (r)
717                 goto bad;
718
719         r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
720         if (r)
721                 goto bad;
722
723         r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
724         if (r)
725                 goto bad;
726
727         /* parse the priority groups */
728         while (as.argc) {
729                 struct priority_group *pg;
730
731                 pg = parse_priority_group(&as, m, ti);
732                 if (!pg) {
733                         r = -EINVAL;
734                         goto bad;
735                 }
736
737                 m->nr_valid_paths += pg->nr_pgpaths;
738                 list_add_tail(&pg->list, &m->priority_groups);
739                 pg_count++;
740                 pg->pg_num = pg_count;
741                 if (!--next_pg_num)
742                         m->next_pg = pg;
743         }
744
745         if (pg_count != m->nr_priority_groups) {
746                 ti->error = ESTR("priority group count mismatch");
747                 r = -EINVAL;
748                 goto bad;
749         }
750
751         ti->private = m;
752         m->ti = ti;
753
754         return 0;
755
756  bad:
757         free_multipath(m);
758         return r;
759 }
760
761 static void multipath_dtr(struct dm_target *ti)
762 {
763         struct multipath *m = (struct multipath *) ti->private;
764
765         flush_workqueue(kmultipathd);
766         free_multipath(m);
767 }
768
769 /*
770  * Map bios, recording original fields for later in case we have to resubmit
771  */
772 static int multipath_map(struct dm_target *ti, struct bio *bio,
773                          union map_info *map_context)
774 {
775         int r;
776         struct mpath_io *mpio;
777         struct multipath *m = (struct multipath *) ti->private;
778
779         if (bio_barrier(bio))
780                 return -EOPNOTSUPP;
781
782         mpio = mempool_alloc(m->mpio_pool, GFP_NOIO);
783         dm_bio_record(&mpio->details, bio);
784
785         map_context->ptr = mpio;
786         bio->bi_rw |= (1 << BIO_RW_FAILFAST);
787         r = map_io(m, bio, mpio, 0);
788         if (r < 0)
789                 mempool_free(mpio, m->mpio_pool);
790
791         return r;
792 }
793
794 /*
795  * Take a path out of use.
796  */
797 static int fail_path(struct pgpath *pgpath)
798 {
799         unsigned long flags;
800         struct multipath *m = pgpath->pg->m;
801
802         spin_lock_irqsave(&m->lock, flags);
803
804         if (!pgpath->path.is_active)
805                 goto out;
806
807         DMWARN("dm-multipath: Failing path %s.", pgpath->path.dev->name);
808
809         pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
810         pgpath->path.is_active = 0;
811         pgpath->fail_count++;
812
813         m->nr_valid_paths--;
814
815         if (pgpath == m->current_pgpath)
816                 m->current_pgpath = NULL;
817
818         queue_work(kmultipathd, &m->trigger_event);
819
820 out:
821         spin_unlock_irqrestore(&m->lock, flags);
822
823         return 0;
824 }
825
826 /*
827  * Reinstate a previously-failed path
828  */
829 static int reinstate_path(struct pgpath *pgpath)
830 {
831         int r = 0;
832         unsigned long flags;
833         struct multipath *m = pgpath->pg->m;
834
835         spin_lock_irqsave(&m->lock, flags);
836
837         if (pgpath->path.is_active)
838                 goto out;
839
840         if (!pgpath->pg->ps.type) {
841                 DMWARN("Reinstate path not supported by path selector %s",
842                        pgpath->pg->ps.type->name);
843                 r = -EINVAL;
844                 goto out;
845         }
846
847         r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
848         if (r)
849                 goto out;
850
851         pgpath->path.is_active = 1;
852
853         m->current_pgpath = NULL;
854         if (!m->nr_valid_paths++ && m->queue_size)
855                 queue_work(kmultipathd, &m->process_queued_ios);
856
857         queue_work(kmultipathd, &m->trigger_event);
858
859 out:
860         spin_unlock_irqrestore(&m->lock, flags);
861
862         return r;
863 }
864
865 /*
866  * Fail or reinstate all paths that match the provided struct dm_dev.
867  */
868 static int action_dev(struct multipath *m, struct dm_dev *dev,
869                       action_fn action)
870 {
871         int r = 0;
872         struct pgpath *pgpath;
873         struct priority_group *pg;
874
875         list_for_each_entry(pg, &m->priority_groups, list) {
876                 list_for_each_entry(pgpath, &pg->pgpaths, list) {
877                         if (pgpath->path.dev == dev)
878                                 r = action(pgpath);
879                 }
880         }
881
882         return r;
883 }
884
885 /*
886  * Temporarily try to avoid having to use the specified PG
887  */
888 static void bypass_pg(struct multipath *m, struct priority_group *pg,
889                       int bypassed)
890 {
891         unsigned long flags;
892
893         spin_lock_irqsave(&m->lock, flags);
894
895         pg->bypassed = bypassed;
896         m->current_pgpath = NULL;
897         m->current_pg = NULL;
898
899         spin_unlock_irqrestore(&m->lock, flags);
900
901         queue_work(kmultipathd, &m->trigger_event);
902 }
903
904 /*
905  * Switch to using the specified PG from the next I/O that gets mapped
906  */
907 static int switch_pg_num(struct multipath *m, const char *pgstr)
908 {
909         struct priority_group *pg;
910         unsigned pgnum;
911         unsigned long flags;
912
913         if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
914             (pgnum > m->nr_priority_groups)) {
915                 DMWARN("invalid PG number supplied to switch_pg_num");
916                 return -EINVAL;
917         }
918
919         spin_lock_irqsave(&m->lock, flags);
920         list_for_each_entry(pg, &m->priority_groups, list) {
921                 pg->bypassed = 0;
922                 if (--pgnum)
923                         continue;
924
925                 m->current_pgpath = NULL;
926                 m->current_pg = NULL;
927                 m->next_pg = pg;
928         }
929         spin_unlock_irqrestore(&m->lock, flags);
930
931         queue_work(kmultipathd, &m->trigger_event);
932         return 0;
933 }
934
935 /*
936  * Set/clear bypassed status of a PG.
937  * PGs are numbered upwards from 1 in the order they were declared.
938  */
939 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed)
940 {
941         struct priority_group *pg;
942         unsigned pgnum;
943
944         if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum ||
945             (pgnum > m->nr_priority_groups)) {
946                 DMWARN("invalid PG number supplied to bypass_pg");
947                 return -EINVAL;
948         }
949
950         list_for_each_entry(pg, &m->priority_groups, list) {
951                 if (!--pgnum)
952                         break;
953         }
954
955         bypass_pg(m, pg, bypassed);
956         return 0;
957 }
958
959 /*
960  * pg_init must call this when it has completed its initialisation
961  */
962 void dm_pg_init_complete(struct path *path, unsigned err_flags)
963 {
964         struct pgpath *pgpath = path_to_pgpath(path);
965         struct priority_group *pg = pgpath->pg;
966         struct multipath *m = pg->m;
967         unsigned long flags;
968
969         /* We insist on failing the path if the PG is already bypassed. */
970         if (err_flags && pg->bypassed)
971                 err_flags |= MP_FAIL_PATH;
972
973         if (err_flags & MP_FAIL_PATH)
974                 fail_path(pgpath);
975
976         if (err_flags & MP_BYPASS_PG)
977                 bypass_pg(m, pg, 1);
978
979         spin_lock_irqsave(&m->lock, flags);
980         if (err_flags) {
981                 m->current_pgpath = NULL;
982                 m->current_pg = NULL;
983         } else if (!m->pg_init_required)
984                 m->queue_io = 0;
985
986         m->pg_init_in_progress = 0;
987         queue_work(kmultipathd, &m->process_queued_ios);
988         spin_unlock_irqrestore(&m->lock, flags);
989 }
990
991 /*
992  * end_io handling
993  */
994 static int do_end_io(struct multipath *m, struct bio *bio,
995                      int error, struct mpath_io *mpio)
996 {
997         struct hw_handler *hwh = &m->hw_handler;
998         unsigned err_flags = MP_FAIL_PATH;      /* Default behavior */
999
1000         if (!error)
1001                 return 0;       /* I/O complete */
1002
1003         if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
1004                 return error;
1005
1006         if (error == -EOPNOTSUPP)
1007                 return error;
1008
1009         spin_lock(&m->lock);
1010         if (!m->nr_valid_paths) {
1011                 if (!m->queue_if_no_path) {
1012                         spin_unlock(&m->lock);
1013                         return -EIO;
1014                 } else {
1015                         spin_unlock(&m->lock);
1016                         goto requeue;
1017                 }
1018         }
1019         spin_unlock(&m->lock);
1020
1021         if (hwh->type && hwh->type->error)
1022                 err_flags = hwh->type->error(hwh, bio);
1023
1024         if (mpio->pgpath) {
1025                 if (err_flags & MP_FAIL_PATH)
1026                         fail_path(mpio->pgpath);
1027
1028                 if (err_flags & MP_BYPASS_PG)
1029                         bypass_pg(m, mpio->pgpath->pg, 1);
1030         }
1031
1032         if (err_flags & MP_ERROR_IO)
1033                 return -EIO;
1034
1035       requeue:
1036         dm_bio_restore(&mpio->details, bio);
1037
1038         /* queue for the daemon to resubmit or fail */
1039         spin_lock(&m->lock);
1040         bio_list_add(&m->queued_ios, bio);
1041         m->queue_size++;
1042         if (!m->queue_io)
1043                 queue_work(kmultipathd, &m->process_queued_ios);
1044         spin_unlock(&m->lock);
1045
1046         return 1;       /* io not complete */
1047 }
1048
1049 static int multipath_end_io(struct dm_target *ti, struct bio *bio,
1050                             int error, union map_info *map_context)
1051 {
1052         struct multipath *m = (struct multipath *) ti->private;
1053         struct mpath_io *mpio = (struct mpath_io *) map_context->ptr;
1054         struct pgpath *pgpath = mpio->pgpath;
1055         struct path_selector *ps;
1056         int r;
1057
1058         r  = do_end_io(m, bio, error, mpio);
1059         if (pgpath) {
1060                 ps = &pgpath->pg->ps;
1061                 if (ps->type->end_io)
1062                         ps->type->end_io(ps, &pgpath->path);
1063         }
1064         if (r <= 0)
1065                 mempool_free(mpio, m->mpio_pool);
1066
1067         return r;
1068 }
1069
1070 /*
1071  * Suspend can't complete until all the I/O is processed so if
1072  * the last path fails we must error any remaining I/O.
1073  * Note that if the freeze_bdev fails while suspending, the
1074  * queue_if_no_path state is lost - userspace should reset it.
1075  */
1076 static void multipath_presuspend(struct dm_target *ti)
1077 {
1078         struct multipath *m = (struct multipath *) ti->private;
1079
1080         queue_if_no_path(m, 0);
1081 }
1082
1083 /*
1084  * Restore the queue_if_no_path setting.
1085  */
1086 static void multipath_resume(struct dm_target *ti)
1087 {
1088         struct multipath *m = (struct multipath *) ti->private;
1089         unsigned long flags;
1090
1091         spin_lock_irqsave(&m->lock, flags);
1092         m->queue_if_no_path = m->saved_queue_if_no_path;
1093         spin_unlock_irqrestore(&m->lock, flags);
1094 }
1095
1096 /*
1097  * Info output has the following format:
1098  * num_multipath_feature_args [multipath_feature_args]*
1099  * num_handler_status_args [handler_status_args]*
1100  * num_groups init_group_number
1101  *            [A|D|E num_ps_status_args [ps_status_args]*
1102  *             num_paths num_selector_args
1103  *             [path_dev A|F fail_count [selector_args]* ]+ ]+
1104  *
1105  * Table output has the following format (identical to the constructor string):
1106  * num_feature_args [features_args]*
1107  * num_handler_args hw_handler [hw_handler_args]*
1108  * num_groups init_group_number
1109  *     [priority selector-name num_ps_args [ps_args]*
1110  *      num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1111  */
1112 static int multipath_status(struct dm_target *ti, status_type_t type,
1113                             char *result, unsigned int maxlen)
1114 {
1115         int sz = 0;
1116         unsigned long flags;
1117         struct multipath *m = (struct multipath *) ti->private;
1118         struct hw_handler *hwh = &m->hw_handler;
1119         struct priority_group *pg;
1120         struct pgpath *p;
1121         unsigned pg_num;
1122         char state;
1123
1124         spin_lock_irqsave(&m->lock, flags);
1125
1126         /* Features */
1127         if (type == STATUSTYPE_INFO)
1128                 DMEMIT("1 %u ", m->queue_size);
1129         else if (m->queue_if_no_path)
1130                 DMEMIT("1 queue_if_no_path ");
1131         else
1132                 DMEMIT("0 ");
1133
1134         if (hwh->type && hwh->type->status)
1135                 sz += hwh->type->status(hwh, type, result + sz, maxlen - sz);
1136         else if (!hwh->type || type == STATUSTYPE_INFO)
1137                 DMEMIT("0 ");
1138         else
1139                 DMEMIT("1 %s ", hwh->type->name);
1140
1141         DMEMIT("%u ", m->nr_priority_groups);
1142
1143         if (m->next_pg)
1144                 pg_num = m->next_pg->pg_num;
1145         else if (m->current_pg)
1146                 pg_num = m->current_pg->pg_num;
1147         else
1148                         pg_num = 1;
1149
1150         DMEMIT("%u ", pg_num);
1151
1152         switch (type) {
1153         case STATUSTYPE_INFO:
1154                 list_for_each_entry(pg, &m->priority_groups, list) {
1155                         if (pg->bypassed)
1156                                 state = 'D';    /* Disabled */
1157                         else if (pg == m->current_pg)
1158                                 state = 'A';    /* Currently Active */
1159                         else
1160                                 state = 'E';    /* Enabled */
1161
1162                         DMEMIT("%c ", state);
1163
1164                         if (pg->ps.type->status)
1165                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1166                                                           result + sz,
1167                                                           maxlen - sz);
1168                         else
1169                                 DMEMIT("0 ");
1170
1171                         DMEMIT("%u %u ", pg->nr_pgpaths,
1172                                pg->ps.type->info_args);
1173
1174                         list_for_each_entry(p, &pg->pgpaths, list) {
1175                                 DMEMIT("%s %s %u ", p->path.dev->name,
1176                                        p->path.is_active ? "A" : "F",
1177                                        p->fail_count);
1178                                 if (pg->ps.type->status)
1179                                         sz += pg->ps.type->status(&pg->ps,
1180                                               &p->path, type, result + sz,
1181                                               maxlen - sz);
1182                         }
1183                 }
1184                 break;
1185
1186         case STATUSTYPE_TABLE:
1187                 list_for_each_entry(pg, &m->priority_groups, list) {
1188                         DMEMIT("%s ", pg->ps.type->name);
1189
1190                         if (pg->ps.type->status)
1191                                 sz += pg->ps.type->status(&pg->ps, NULL, type,
1192                                                           result + sz,
1193                                                           maxlen - sz);
1194                         else
1195                                 DMEMIT("0 ");
1196
1197                         DMEMIT("%u %u ", pg->nr_pgpaths,
1198                                pg->ps.type->table_args);
1199
1200                         list_for_each_entry(p, &pg->pgpaths, list) {
1201                                 DMEMIT("%s ", p->path.dev->name);
1202                                 if (pg->ps.type->status)
1203                                         sz += pg->ps.type->status(&pg->ps,
1204                                               &p->path, type, result + sz,
1205                                               maxlen - sz);
1206                         }
1207                 }
1208                 break;
1209         }
1210
1211         spin_unlock_irqrestore(&m->lock, flags);
1212
1213         return 0;
1214 }
1215
1216 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1217 {
1218         int r;
1219         struct dm_dev *dev;
1220         struct multipath *m = (struct multipath *) ti->private;
1221         action_fn action;
1222
1223         if (argc == 1) {
1224                 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path")))
1225                         return queue_if_no_path(m, 1);
1226                 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path")))
1227                         return queue_if_no_path(m, 0);
1228         }
1229
1230         if (argc != 2)
1231                 goto error;
1232
1233         if (!strnicmp(argv[0], MESG_STR("disable_group")))
1234                 return bypass_pg_num(m, argv[1], 1);
1235         else if (!strnicmp(argv[0], MESG_STR("enable_group")))
1236                 return bypass_pg_num(m, argv[1], 0);
1237         else if (!strnicmp(argv[0], MESG_STR("switch_group")))
1238                 return switch_pg_num(m, argv[1]);
1239         else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
1240                 action = reinstate_path;
1241         else if (!strnicmp(argv[0], MESG_STR("fail_path")))
1242                 action = fail_path;
1243         else
1244                 goto error;
1245
1246         r = dm_get_device(ti, argv[1], ti->begin, ti->len,
1247                           dm_table_get_mode(ti->table), &dev);
1248         if (r) {
1249                 DMWARN("dm-multipath message: error getting device %s",
1250                        argv[1]);
1251                 return -EINVAL;
1252         }
1253
1254         r = action_dev(m, dev, action);
1255
1256         dm_put_device(ti, dev);
1257
1258         return r;
1259
1260 error:
1261         DMWARN("Unrecognised multipath message received.");
1262         return -EINVAL;
1263 }
1264
1265 /*-----------------------------------------------------------------
1266  * Module setup
1267  *---------------------------------------------------------------*/
1268 static struct target_type multipath_target = {
1269         .name = "multipath",
1270         .version = {1, 0, 4},
1271         .module = THIS_MODULE,
1272         .ctr = multipath_ctr,
1273         .dtr = multipath_dtr,
1274         .map = multipath_map,
1275         .end_io = multipath_end_io,
1276         .presuspend = multipath_presuspend,
1277         .resume = multipath_resume,
1278         .status = multipath_status,
1279         .message = multipath_message,
1280 };
1281
1282 static int __init dm_multipath_init(void)
1283 {
1284         int r;
1285
1286         /* allocate a slab for the dm_ios */
1287         _mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io),
1288                                         0, 0, NULL, NULL);
1289         if (!_mpio_cache)
1290                 return -ENOMEM;
1291
1292         r = dm_register_target(&multipath_target);
1293         if (r < 0) {
1294                 DMERR("%s: register failed %d", multipath_target.name, r);
1295                 kmem_cache_destroy(_mpio_cache);
1296                 return -EINVAL;
1297         }
1298
1299         kmultipathd = create_workqueue("kmpathd");
1300         if (!kmultipathd) {
1301                 DMERR("%s: failed to create workqueue kmpathd",
1302                                 multipath_target.name);
1303                 dm_unregister_target(&multipath_target);
1304                 kmem_cache_destroy(_mpio_cache);
1305                 return -ENOMEM;
1306         }
1307
1308         DMINFO("dm-multipath version %u.%u.%u loaded",
1309                multipath_target.version[0], multipath_target.version[1],
1310                multipath_target.version[2]);
1311
1312         return r;
1313 }
1314
1315 static void __exit dm_multipath_exit(void)
1316 {
1317         int r;
1318
1319         destroy_workqueue(kmultipathd);
1320
1321         r = dm_unregister_target(&multipath_target);
1322         if (r < 0)
1323                 DMERR("%s: target unregister failed %d",
1324                       multipath_target.name, r);
1325         kmem_cache_destroy(_mpio_cache);
1326 }
1327
1328 EXPORT_SYMBOL_GPL(dm_pg_init_complete);
1329
1330 module_init(dm_multipath_init);
1331 module_exit(dm_multipath_exit);
1332
1333 MODULE_DESCRIPTION(DM_NAME " multipath target");
1334 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
1335 MODULE_LICENSE("GPL");